A conventional transmission comprises a continuously variable transmission mechanism (a variator), and a stepped auxiliary transmission mechanism that is switched between a plurality of forward gear positions selectively. With this type of transmission, in comparison with a continuously variable transmission constituted by only a variator, a shift region can be expanded by the auxiliary transmission mechanism, enabling improvements in engine efficiency and fuel efficiency.
JP2012-57710A discloses a conventional transmission of this type having a so-called manual shift mode, in which control is performed to allow a driver to select a speed ratio by performing a shift operation. JP2012-57710A discloses a continuously variable transmission having a manual shift mode in which a through speed ratio constituting a speed ratio of the entire transmission is caused to reach a target speed ratio by modifying only a speed ratio of a variator, whereupon an auxiliary transmission mechanism is shifted while varying the speed ratio of the variator in response to variation in a speed ratio of the auxiliary transmission mechanism so that the through speed ratio does not vary.
Further, as described in JP2000-120860A, when a multiple shift from a first gear position to a second gear position and from the second gear position to the first gear position is performed repeatedly in a stepped automatic transmission, a thermal load exerted on a frictional engagement element may increase, leading to a reduction in durability. To prevent this problem, JP2000-120860A discloses a control apparatus for an automatic transmission, the control apparatus comprising multiple shift detecting unit for detecting a multiple shift, and multiple shift prohibiting unit for prohibiting the multiple shift when an integrated value reaches a set value while the multiple shift is underway.